1. Field of the Invention
The present invention relates to a homogenizer, and particularly to a homogenizer for homogenizing an emulsion by jetting out the emulsion from spaced apart microgaps in order to break up the liquid components into minute particles for effecting the homogenization.
2. Prior Art
The process of homogenization of emulsion or dispersed solution is mainly applied to separating fat globules of milk into fine particles so that the formation of cream is prevented or delayed, or for treating dispersed solutions containing pigments, chemicals, etc.
The generally used process for homogenization has been to eject a liquid, that is under a high pressure as high as 100-210 kg/cm.sup.2 applied by a high pressure pump, from a micro-slit formed between valves, then to let the sprayed out liquid smash against a wall surface.
The working mechanism in homogenization is not fully clarified theoretically, but the following is assumed. That there is a very strong shearing force acting upon the liquid components during the passage of the liquid through the microgap, a sudden change the liquid undergoes when it is rapidly pushed out from the high pressure area to the low pressure area, i.e. the cavitation, and the impact destruction cause when the liquid, ejected from the microgap, smashes against the wall surface and all contribute to the subdivision of the liquid components into minute pieces, thereby effecting homogenization.
Accordingly, the degree of homogenization is dependent on the factors, such as the difference in pressure of the liquid before and after passage through the microgap, the impact force upon colliding against the collision wall, and the presence or absence of something blocking the flow of the liquid.
Conventional homogenizers using the abovementioned homogenization process have been constructed as a single valve system homogenizer including ring-form spaced apart microgaps formed by a couple of valve seats and a valve, collision walls formed of circumferential surfaces provided at certain intervals by locating them outside of the spaced apart microgaps, one-directional outlets for the homogenized liquid, and a plunger pump for feeding the liquid at high pressure.
If the homogenizing capacity is to be doubled by using this conventional single valve system homogenizer, the diameter of the valve must be doubled to double the circumferential length.
When the diameter of the valve is doubled, the valve area becomes four times larger in proportion to the square of the diameter; and if the valve area that is increased to four times is to receive the high liquid pressure, the thrust applied to the valve also must be increased four times. Accordingly, as the diameter of the valve is made larger, the valve becomes subjected to a sharply growing thrust. In parallel with it, the structure of each component part of the system has to be reinforced to withstand such strong thrust. This in return requires tremendously high cost for the equipment. Therefore, in reality, it is dangerous and impractical for the liquid pressure to exceed a certain level.
Consequently, in order to increase the operational capacity by using this type of homogenizer, it is necessary to increase the number of homogenizers. However, to implement such an arrangement requires an increase in cost for the equipment as well as the cost for the power used, and it defeats the purpose which is the improvement in efficiency.
Furthermore, in this type of conventional homogenizer, the outlet for the homogenized liquid after colliding with the collision wall is provided only for one-directional flow. As a result of the liquid scattering in all directions after clashing into the collision wall, the portion that is splashed in directions other than in the direction of the outlet is formed to shift its direction, after colliding with the other wall surface, to that heading to the outlet. This portion of the homogenized liquid that is formed to change its flowing direction interferes with the other liquid portion ejection from the microgaps as well as its scattering from the collision wall, and checks the flow of such other liquid portion, thereby causing lowered homogenizing performance.
In light of such shortcomings of the current homogenization technique, an improvement has been called for to obtain a homogenizer equipped with higher performance and higher operational efficiency.